Pathway · 5 proteins
Pantothenate and CoA biosynthesis
Proteins of this group that KEGG places on its “Pantothenate and CoA biosynthesis” map for Aquifex aeolicus.
How it works
This map shows how pantothenate (vitamin B5) is made and turned into coenzyme A. The proteins here build pantoate from a valine-pathway intermediate and join it to beta-alanine to make pantothenate. They share their first steps with the branched-chain amino acid pathways.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| 2-dehydropantoate 2-reductase | 1.1.1.169 | (R)-pantoate + NADP(+) = 2-dehydropantoate + NADPH + H(+) | — | 310 | Step named |
| Probable branched-chain-amino-acid aminotransferase | 2.6.1.42 | L-leucine + 2-oxoglutarate = 4-methyl-2-oxopentanoate + L-glutamate | — | 311 | Step named |
| 3-methyl-2-oxobutanoate hydroxymethyltransferase | 2.1.2.11 | (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + 3-methyl-2-oxobutanoate + H2O = 2-dehydropantoate + (6S)-5,6,7,8-tetrahydrofolate | Mg(2+) | 265 | Step named |
| Pantothenate synthetase | 6.3.2.1 | (R)-pantoate + beta-alanine + ATP = (R)-pantothenate + AMP + diphosphate + H(+) | — | 282 | Step named |
| Acetolactate synthase | 2.2.1.6 | 2 pyruvate + H(+) = (2S)-2-acetolactate + CO2 | Mg(2+) | 585 | Step named |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Ketol-acid reductoisomerase (NADP(+))Home: Branched-chain amino acids | 1.1.1.86 | (2R)-2,3-dihydroxy-3-methylbutanoate + NADP(+) = (2S)-2-acetolactate + NADPH + H(+) | Mg(2+) | 333 | Step named |
| Acetolactate synthase small subunitHome: Branched-chain amino acids | 2.2.1.6 | 2 pyruvate + H(+) = (2S)-2-acetolactate + CO2 | — | 192 | Step named |
| Dihydroxy-acid dehydrataseHome: Branched-chain amino acids | 4.2.1.9 | (2R)-2,3-dihydroxy-3-methylbutanoate = 3-methyl-2-oxobutanoate + H2O | Mg(2+), [2Fe-2S] cluster | 555 | Step named |
| Type III pantothenate kinaseHome: Coenzyme A | 2.7.1.33 | (R)-pantothenate + ATP = (R)-4'-phosphopantothenate + ADP + H(+) | K(+) | 229 | Step named |
| Dephospho-CoA kinaseHome: Coenzyme A | 2.7.1.24 | 3'-dephospho-CoA + ATP = ADP + CoA + H(+) | — | 196 | Step named |
| Phosphopantetheine adenylyltransferaseHome: Coenzyme A | 2.7.7.3 | (R)-4'-phosphopantetheine + ATP + H(+) = 3'-dephospho-CoA + diphosphate | Mg(2+) | 161 | Step named |
| Coenzyme A biosynthesis bifunctional protein CoaBCHome: Coenzyme A | 4.1.1.36; 6.3.2.5 | (R)-4'-phosphopantothenate + L-cysteine + CTP = N-[(R)-4-phosphopantothenoyl]-L-cysteine + CMP + diphosphate + H(+) | FMN, Mg(2+) | 388 | Step named |
| Holo-[acyl-carrier-protein] synthaseHome: Not yet placed in a pathway | 2.7.8.7 | apo-[ACP] + CoA = holo-[ACP] + adenosine 3',5'-bisphosphate + H(+) | Mg(2+) | 122 | Step named |
| Aspartate 1-decarboxylaseHome: Not yet placed in a pathway | 4.1.1.11 | L-aspartate + H(+) = beta-alanine + CO2 | — | 124 | Step named |
| Nucleoside triphosphate pyrophosphohydrolaseHome: Purine metabolism | 3.6.1.8 | ATP + H2O = AMP + diphosphate + H(+) | — | 257 | Unspecified |
Origins
Could pantothenate (vitamin B5), the core of coenzyme A, have been supplied before this pathway existed?
Miller and Schlesinger reported prebiotic syntheses of pantoic acid and pantothenic acid (1993), and Keefe, Newton and Miller reported a possible prebiotic synthesis of pantetheine (1995).
The cell builds coenzyme A in several steps from pantothenate, cysteine and ATP. Five proteins of the minimal set serve this pathway, and every acyl-carrying reaction in the cell waits on it.
From the books: Ribas de Pouplana (ed.), The Genetic Code and the Origin of Life, p. 74.
The wider question for this part of the cell: origins for manufacturing cofactors and vitamins.
Sources
- KEGG map aae00770 (enzymes of this organism highlighted)
Other pathways in this group: Heme and quinones · Biotin and lipoate · NAD and flavins · Thiamine and pyridoxal · Folate and pterin chemistry · Lipid and cofactor connections · Coenzyme A · Aspartate-family branches · Amino-acid connections · Folate-linked carbon transfer · Serine, glycine and sulfur · Folate biosynthesis · Oxidative phosphorylation · Thiamine metabolism · Glycine, serine and threonine metabolism · Riboflavin metabolism · Nicotinate and nicotinamide metabolism · Biotin metabolism · Cysteine and methionine metabolism · Porphyrin metabolism · Pyruvate metabolism · Not yet placed in a pathway